US3469212A - Modulator employing a pair of transistors biased for class ab operation - Google Patents

Modulator employing a pair of transistors biased for class ab operation Download PDF

Info

Publication number
US3469212A
US3469212A US590983A US3469212DA US3469212A US 3469212 A US3469212 A US 3469212A US 590983 A US590983 A US 590983A US 3469212D A US3469212D A US 3469212DA US 3469212 A US3469212 A US 3469212A
Authority
US
United States
Prior art keywords
voltage
transistors
modulator
carrier
transformer
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
US590983A
Other languages
English (en)
Inventor
Heinz Georg Karl
Borje Mats Ingvar Roos
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Telefonaktiebolaget LM Ericsson AB
Original Assignee
Telefonaktiebolaget LM Ericsson AB
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Telefonaktiebolaget LM Ericsson AB filed Critical Telefonaktiebolaget LM Ericsson AB
Application granted granted Critical
Publication of US3469212A publication Critical patent/US3469212A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Images

Classifications

    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03C—MODULATION
    • H03C1/00—Amplitude modulation
    • H03C1/36—Amplitude modulation by means of semiconductor device having at least three electrodes
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03F—AMPLIFIERS
    • H03F3/00—Amplifiers with only discharge tubes or only semiconductor devices as amplifying elements
    • H03F3/20—Power amplifiers, e.g. Class B amplifiers, Class C amplifiers
    • H03F3/21—Power amplifiers, e.g. Class B amplifiers, Class C amplifiers with semiconductor devices only

Definitions

  • a modulator includes a pair of transistors whose bases are connected to the arms of a centertapped secondary winding of an input transformer which receives the modulating signals across its primary winding.
  • the collectors of the transistors are connected to the arms of a centertapped primary winding of an output transformer whose secondary winding transmits modulated signals.
  • the emitters of the transistors are interconnected by a centertapped resistor.
  • a source of operating voltage is connected between the centertap of the resistor and the centertap of the primary winding of the output transformer.
  • a voltage divider is connected across the operating voltage source with the output of the voltage divider connected to the centertap of the secondary winding of the input transformer to bias the base electrodes to class AB operation.
  • the carrier signal is applied between the centertap of the secondary winding of the input transformer and a terminal of the source of operating voltage.
  • the present invention refers to an arrangement for modulators comprising at least one pair of transistors which are connected in parallel for the carrier voltage and in push-pull for the signal voltage.
  • the pair of transistors have their emitter electrodes connected by means of a resistance provided with a first tap, and their base electrodes connected by means of a winding on a first transformer, provided with a second tap.
  • the signal voltage is applied to the modulator via the transformer and the carrier voltage is applied to the modulator via the first and second collector taps.
  • the electrodes of the transistor are connected by means of a second transformer provided with a third tap, through which second transformer the modulated signal voltage is derived from the modulator.
  • a direct voltage supply is applied to the modulator via 'ice so that a constant carrier voltage is always supplied to the modulator.
  • Another method is to use a carrier generator to the output of which has been connected a diode limiter. A square wave is obtained from this diode limiter which is then filtered in a low pass filter. The signal obtained from the low pass filter, which signal is supplied to the modulator, will, accordingly be less dependent on variations in the carrier voltage.
  • a modulator of the type indicated above is usually so designed that the transistors work in class B-operation.
  • the collector current obtained then consists of a train of pulses of the same height.
  • the pulse height will thus vary in step with the frequency of the signal voltage.
  • a modulator connection of the indicated type now demands a rather high carrier power in order that the transistors should be conducting. This power is dependent on the size of the resistance that interconnect the emitter electrodes of the transistors. Then however the risk will arise that the carrier voltage becomes too high.
  • the base emitter diode in the transistors must have a larger permitted blocking voltage than the applied negative half-wave of the carrier voltage.
  • the base current is directly dependent on the amplitude of the carrier voltage and therefore also the output voltage will be affected by the variations of the carrier voltage. Furthermore there is needed, in order to adapt the carrier signal input to the impedance of the source of the carrier voltage, for example ohms, a transformer or an impedance transforming link. Already at a frequency of 5 or 6 mHz. problems will arise in designing such impedance matching links in practice.
  • An object of this invention is to avoid the disadvantages mentioned above; variations in the amplitude of the carrier voltage, high necessary carrier power and difiiculties in matching to the carrier source.
  • An arrangement according to the invention is thus mainly characterized by the direct voltage supply of the modulator being provided with a voltage divider which is connected to the base electrodes of the transistors, the voltage divider being so arranged that the transistors are given such a base bias that they work in class AB-operation.
  • FIG. 1 shows an arrangement in principle according to the invention
  • FIG. 3 shows the base current as a function of the base-emitter-voltage
  • FIG. 3 shows a practical embodiment in accordance with the invention.
  • FIG. 1 shows a modulator circuit comprising the transistors T1 and T2 which are connected to an input transformer Tr1 and to an output transformer Tr2.
  • the signal voltage is supplied through the terminals 1, 1 and from the output transformer Tr2 the modulated signal will be derived through the terminals 2, 2.
  • a resistance R3 is connected and parallelly to the primary winding of the transformer Tr2 a resistance R4 is connected.
  • the emitter electrodes of the transistors T1 and T2 are connected by means of two series connected resistances R1 and R2. Between the conmeeting point A of these resistances and a centre tap on the secondary winding of the input transformer the carrier signal is supplied to the modulator through the terminals 3, 3.
  • the bases of the transistors are given a certain bias voltage.
  • This bias is here chosen so that the transistors are to work in class AB-operation.
  • the base is thus biassed with a certain direct voltage UBO.
  • the direct voltage is then set so that a certain quiescent current IBO passes through the transistors.
  • FIG. 2 where the base current is drawn as a function of the base emitter voltage.
  • FIG. 3 An embodiment of the modulator according to the invention intended for practical use is shown in FIG. 3.
  • the modulator comprises besides those components which have been indicated in connection with the description of FIG. 1 a resistance connected amplifier stage connected between the voltage divider and the bases of the transistors T1 and T2.
  • the amplifier stage has an amplification element the transistor T3, the bias voltage of which is regulated by means of the resistances R12 and R13.
  • Across the input 3, 3 of the carrier signal there is connected a resistance R14, by means of which the input impedance of the input 3, 3 can be controlled.
  • a filter link consisting of the resistance R and the capacitor C3 which are connected between the power supply and ground.
  • the voltage divider which here consists of the resistances R9, R10 and R11 and the transistor T3. From the collector of the transistor T3 that voltage will be derived which is supplied to the bases of the transistors T1 and T2 via the centre tap of the secondary winding of the input transformer Trl. Through the direct voltage supply is furthermore connected a protection circuit for the transistors T1 and T2 which protection circuit comprises the resistances R5, R6 and the capacitor C1.
  • a modulator comprising:
  • first and second transistors each having base, emitter and collector electrodes
  • an input transformer having a primary winding and a centertapped secondary winding, said primary winding being adapted to receive an input modulating signal
  • an output transformer having a centertapped primary winding and a secondary winding, said secondary winding being adapted to transmit an output modulated signal
  • a source of operating voltage having first and second terminals
  • a voltage divider means having an output terminal
  • said voltage divider means comprises a third transistor having base, collector and emitter electrodes, first resistor means for connecting the emitter electrode of said third transistor to one terminal of said source of operating voltage, second resistor means for connecting the collector electrode of said third transistor to the other terminal of said source of operating potential, means for establishing an operating bias to the base electrode of said third transistor, means for connecting the collector electrode of said third transistor to the centertap of the secondary winding of said input transformer, and means connected to the base electrode of said third transistor for receiving the carrier signal,
US590983A 1965-11-23 1966-10-31 Modulator employing a pair of transistors biased for class ab operation Expired - Lifetime US3469212A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
SE15094/65A SE330560B (xx) 1965-11-23 1965-11-23

Publications (1)

Publication Number Publication Date
US3469212A true US3469212A (en) 1969-09-23

Family

ID=20300132

Family Applications (1)

Application Number Title Priority Date Filing Date
US590983A Expired - Lifetime US3469212A (en) 1965-11-23 1966-10-31 Modulator employing a pair of transistors biased for class ab operation

Country Status (5)

Country Link
US (1) US3469212A (xx)
DE (1) DE1541694A1 (xx)
GB (1) GB1094556A (xx)
NO (1) NO122132B (xx)
SE (1) SE330560B (xx)

Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3571761A (en) * 1969-05-01 1971-03-23 Hughues Aircraft Co Transistorized amplitude modulation circuit with current control
US4369522A (en) * 1978-07-03 1983-01-18 Motorola, Inc. Singly-balanced active mixer circuit
US4449245A (en) * 1982-03-22 1984-05-15 Motorola Inc. High gain balanced mixer
US20110181360A1 (en) * 2010-01-25 2011-07-28 Yang Edward Li Stacked linear power amplifier with capacitor feedback and resistor isolation
WO2012058122A1 (en) * 2010-10-27 2012-05-03 Peregrine Semiconductor Corporation Method, system, and apparatus for rf and dc switching
US8350624B2 (en) 2010-09-01 2013-01-08 Peregrine Semiconductor Corporation Amplifiers and related biasing methods and devices
US8559907B2 (en) 2004-06-23 2013-10-15 Peregrine Semiconductor Corporation Integrated RF front end with stacked transistor switch
US9264053B2 (en) 2011-01-18 2016-02-16 Peregrine Semiconductor Corporation Variable frequency charge pump
US9960737B1 (en) 2017-03-06 2018-05-01 Psemi Corporation Stacked PA power control

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2521116A (en) * 1949-03-05 1950-09-05 Bell Telephone Labor Inc Wave translating device
US3237129A (en) * 1962-03-26 1966-02-22 Gen Electric Co Ltd Push-pull modulator circuit with means to vary the output level of the carrier and sidebands
US3239780A (en) * 1962-09-05 1966-03-08 Ericsson Telefon Ab L M Modulator having variable magnitude impedance for regulating the operating attenuation

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2521116A (en) * 1949-03-05 1950-09-05 Bell Telephone Labor Inc Wave translating device
US3237129A (en) * 1962-03-26 1966-02-22 Gen Electric Co Ltd Push-pull modulator circuit with means to vary the output level of the carrier and sidebands
US3239780A (en) * 1962-09-05 1966-03-08 Ericsson Telefon Ab L M Modulator having variable magnitude impedance for regulating the operating attenuation

Cited By (20)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3571761A (en) * 1969-05-01 1971-03-23 Hughues Aircraft Co Transistorized amplitude modulation circuit with current control
US4369522A (en) * 1978-07-03 1983-01-18 Motorola, Inc. Singly-balanced active mixer circuit
US4449245A (en) * 1982-03-22 1984-05-15 Motorola Inc. High gain balanced mixer
US9369087B2 (en) 2004-06-23 2016-06-14 Peregrine Semiconductor Corporation Integrated RF front end with stacked transistor switch
US11588513B2 (en) 2004-06-23 2023-02-21 Psemi Corporation Integrated RF front end with stacked transistor switch
US11070244B2 (en) 2004-06-23 2021-07-20 Psemi Corporation Integrated RF front end with stacked transistor switch
US8559907B2 (en) 2004-06-23 2013-10-15 Peregrine Semiconductor Corporation Integrated RF front end with stacked transistor switch
US8649754B2 (en) 2004-06-23 2014-02-11 Peregrine Semiconductor Corporation Integrated RF front end with stacked transistor switch
US10715200B2 (en) 2004-06-23 2020-07-14 Psemi Corporation Integrated RF front end with stacked transistor switch
US9680416B2 (en) 2004-06-23 2017-06-13 Peregrine Semiconductor Corporation Integrated RF front end with stacked transistor switch
US20110181360A1 (en) * 2010-01-25 2011-07-28 Yang Edward Li Stacked linear power amplifier with capacitor feedback and resistor isolation
US8487706B2 (en) 2010-01-25 2013-07-16 Peregrine Semiconductor Corporation Stacked linear power amplifier with capacitor feedback and resistor isolation
US8350624B2 (en) 2010-09-01 2013-01-08 Peregrine Semiconductor Corporation Amplifiers and related biasing methods and devices
US9509263B2 (en) 2010-09-01 2016-11-29 Peregrine Semiconductor Corporation Amplifiers and related biasing methods and devices
US8970303B2 (en) 2010-09-01 2015-03-03 Peregrine Semiconductor Corporation Amplifiers and related biasing methods and devices
US8373490B2 (en) 2010-10-27 2013-02-12 Peregrine Semiconductor Corporation Method, system, and apparatus for RF and DC switching
WO2012058122A1 (en) * 2010-10-27 2012-05-03 Peregrine Semiconductor Corporation Method, system, and apparatus for rf and dc switching
US9413362B2 (en) 2011-01-18 2016-08-09 Peregrine Semiconductor Corporation Differential charge pump
US9264053B2 (en) 2011-01-18 2016-02-16 Peregrine Semiconductor Corporation Variable frequency charge pump
US9960737B1 (en) 2017-03-06 2018-05-01 Psemi Corporation Stacked PA power control

Also Published As

Publication number Publication date
GB1094556A (en) 1967-12-13
NO122132B (xx) 1971-05-24
DE1541694A1 (de) 1970-04-09
SE330560B (xx) 1970-11-23

Similar Documents

Publication Publication Date Title
US2486776A (en) Self-biased electric translating device
US4130765A (en) Low supply voltage frequency multiplier with common base transistor amplifier
US3469212A (en) Modulator employing a pair of transistors biased for class ab operation
JPS58146116A (ja) 電子利得制御装置
US2409897A (en) High-frequency pulse generator
US3470446A (en) Positive dc to positive dc converter
US3965447A (en) Synthetic reactor circuit
US3098200A (en) Semiconductor oscillator and amplifier
US3803423A (en) Means for effecting continuously variable impedance elements
US4019114A (en) Circuit arrangement for the ungrounded transmission of signals through testing points in communication facilities
US3538342A (en) Device for controlling an inverter
US4314106A (en) Line circuit
US3090929A (en) Controller circuitry with pulse width modulator
US3424858A (en) Line communications system including an electric amplifier composed of similar transistors
US3329910A (en) Transformerless modulating and filtering apparatus
US3783304A (en) Constant pulse width generator
US3660685A (en) Pulse generating transformer circuit
US4011410A (en) Communication system interface circuits
US4713838A (en) Amplifier with double rail output
US3854100A (en) Push-pull amplifying devices with class d transistorized amplifiers
US3421020A (en) Step voltage generator
US3068421A (en) Transistorized pulse modulation converter and demodulator
US3022465A (en) Plural-transistor circuit with fuse means
US4133986A (en) Subscriber's line equipment for a telephone exchange
US3440564A (en) Astable relaxation oscillator including a bilateral limiter in the output circuit